The present disclosure relates to a system and method for magnetic density separation (MDS).
Density separation is used in raw materials processing for the classification of mixed streams into streams with products (e.g. particles) of different types of materials. In an accurate form of density separation, a liquid medium is used in which the lighter material float and the heavier materials sink. The process requires a liquid medium that has a density that is intermediate between the density of the light and heavy materials in the feed, yet is inexpensive and safe. In magnetic density separation this is provided using a magnetic liquid. The magnetic liquid has a material density which is comparable to that of water. However, when a gradient magnetic field is applied to the magnetic liquid, the force on a volume of the liquid is the sum of gravity and the magnetic force. In this way, it is possible to make the liquid artificially light or heavy, resulting in an amplified density gradient.
For example, EP 2 247 386 B1 describes a method and apparatus for separating solid particles of different densities, using a magnetic process fluid. The solid particles are mixed in a small partial flow of the process fluid. The small turbulent partial flow is added to a large laminar partial flow of the process fluid, after which the obtained mixture of the respective partial process fluids is conducted over, under, or through the middle of a magnet configuration. Particles are separated into lighter particles at the top of the laminar process fluid and heavier particles at the bottom of the laminar process fluid, each of which are subsequently removed with the aid of a splitter. The materials of low density and the materials of high density are separated from the respective process streams, dried and stored and finally, the process streams are returned to the original starting process fluid streams.
The present disclosure aims to improve process continuity while maintaining a high separation efficiency, in particular by alleviating material build-up and clogging of products at the splitter and other surfaces with minimal disturbance to the process flow.